1. Field of the Invention
This invention relates to new and improved earth drilling bits having an improved retaining pin securing ball bearings in place in the bearing race for the cutter elements of the drill bits.
2. Brief Description of the Prior Art
In the manufacture of earth drilling bits, and more particularly three cutter bits of the conical cutter element type, the cutters are provided with ball bearings secured in a bearing race and introduced through a hole extending to the outside of the cutter support. A plug is normally provided in this hole to secure the bearings in place, which plug has an end portion cut to a curvature fitting the curvature of the bearing race. Murdoch et al U.S. Pat. No. 3,765,495 and Schumacher et al U.S. Pat. No. 3,847,234 disclose bearing retaining pins for earth boring drill bits which are typical of those in present commercial use and typical of the prior art in general. The bearing pins are introduced into the hole through which the bearings are inserted and have an end portion cut to fit the bearing race. The bearing retaining pins, however, are cut asymmetrically and must be aligned accurately to insure that the curvature of the end of the pin fits accurately with the curvature of the bearing race.